Flow through type drying apparatus

ABSTRACT

.Iadd.Apparatus for method of vacuum freeze-drying frozen granular material in spaced, substantially vertical product beds is provided by vertical cell units designed for this purpose. Sublimed water vapors are conveyed from the product beds to the condensing area by open spaces between said product beds. The open spaces contain heating means for supplying heat of sublimation to the frozen material within the product beds..Iaddend.

This invention relates to a drying apparatus, and more particularly, toa flow through type drying apparatus which may be utilized for vacuum orfreeze drying of various products.

Heretofore, it has been conventional in the art relating to dryingapparatus to vacuum dry or freeze dry products on a batch basis. Thatis, a housing was provided and trays or containers of the product to bedried were placed in the housing. At the completion of the cycle, thetrays or containers of the product were removed from the housing and anew batch of the product was placed within the housing. Such apparatussuffers from the defect that excess material handling is required.

The apparatus of the present invention overcomes the disadvantage of theprior art by providing a drying apparatus which requires a minimum ofmaterial handling. This is accomplished by making the apparatus a flowthrough type. By the terminology "floor through type," is meant that theproducts to be dried are placed into a housing from one end thereof andremoved from an opposite end in a manner which eliminates the necessityfor discrete trays or containers which support the products before,during and after the drying cycle. Preferably, the products to be driedare fed into the drying apparatus from a hopper or the like. Also, thehousing is preferably provided with a movable closure means whichenables the dried product to be removed from the housing due to gravity.

The drying apparatus of the present invention may be utilized for vacuumdrying or freeze drying. As is well known to those skilled in the art,vacuum drying embraces the concept of subjecting articles to a reducedpressure and a temperature above room temperature. Freeze dryingcomprehends subjecting frozen articles to an evacuated atmosphere and acontrolled elevated temperature for a sufficient length of time so thatall moisture in the articles will be sublimed. Hence, the moisture inthe frozen articles will change from a solid to a vapor state withoutpassing through a transition phase wherein the moisture is a liquid. Anyone of a wide variety of articles may be freeze dried in accordance withthe present invention. For example, the present invention may beutilized to freeze dry food products, coffee, pharmaceuticals, blood,milk, biological specimens, fruit extracts, etc.

Industry is making wide use of freeze drying techniques. Freeze dryingof products is desirable since it permits the products to be storedalmost indefinitely without refrigeration. Food products may beprocessed in this manner without impairment or loss of fresh naturalflavor, vitamin content, quality, etc.

It is an object of the present invention to provide a novel dryingapparatus.

It is another object of the present invention to provide a novel dryingapparatus of the flow through type which substantially reduces theamount of materials handling required.

It is another object of the present invention to provide a novel dryingapparatus which is designed so that articles or products to be dried areinserted into a housing from one end thereof and removed from anopposite end thereof.

It is another object of the present invention to provide a novel dryingapparatus wherein dried products are permitted to be removed from theapparatus by the gravitational effect thereon.

It is another object of the present invention to provide a novel dryingapparatus which may be in modular form.

It is another object of the present invention to provide a novel dryingapparatus wherein a bottom wall of a housing constitutes a dischargecontrol member for products which have been dried.

It is another object of the present invention to provide a novel freezedrying apparatus which substantially reduces material handling beforeand after the drying cycle.

It is another object of the present invention to provide a dryingapparatus which facilitates mechanical conveyance of articles to andfrom the apparatus.

Other objects will appear hereinafter.

For the purpose of illustrating the invention there is shown in thedrawings forms which are presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a partial perspective view of the apparatus of the presentinvention.

FIG. 2 is a sectional view taken along the lines 2--2 in FIG. 1.

FIG. 3 is a sectional view taken along the lines 3--3 in FIG. 1.

FIG. 4 is an enlarged sectional view taken along the lines 4--4 in FIG.3.

FIG. 5 is a perspective view of another embodiment of the containerwhich may be utilized with the apparatus of the present invention.

Referring to the drawing in detail, wherein like numerals indicate likeelements, there is shown in FIG. 1 a drying apparatus designatedgenerally as 10.

The apparatus 10 may include a plurality of housings 12-16interconnected in modular form. For the purposes of the presentdiscussion, only housing 12 will be described in detail. It will beappreciated that the housings 14 and 16 are identical with housing 12.By making the housings in modular form, any desired number of housingsmay be interconnected and utilized with a single exhaust system asdictated by production requirements.

As shown more clearly in FIGS. 2 and 3, the housing 12 is provided witha front wall 18 and a back wall 20 interconnected by side walls 22 and24. The housing 12 is provided with a top wall 26. The top wall 26 hasone edge pivotally secured to the rear wall 20 by means of a hinge orthe like thereby facilitating movement of the top wall 26 to the phantomposition illustrated in FIG. 1.

The housing 12 is provided with a bottom wall 30 which is likewisepivotably secured to the rear wall 20. Hence, the bottom wall 30 may bepivoted to the phantom disposition illustrated in FIG. 1. The innersurface of the top wall 26 is provided with a deformable gasket 28 whichis adapted to cooperate with the upper edge of the front, rear and sidewalls thereby providing a hermetic seal in the closed disposition of thetop wall 26. A similar gasket 32 is provided for the bottom wall 30. Anysuitable device may be provided to releasably secure the top and bottomwalls in their closed disposition. For example, a conventional hasp 34may be provided as illustrated more clearly in FIG. 1.

As shown more clearly in FIGS. 2 and 3, the interior of the housing 12is preferably provided with a layer of reflective material 36. The layerof reflective material 36 reduces the tendency of the housing 12 toabsorb heat as will be made clear hereinafter. A source of heat isprovided adjacent the side walls 22 and 24 and in a central portion ofthe housing 12 substantially equidistant from the side walls 22 and 24.Such source of heat may be a hollow flat housing through which steam orhot water may be circulated. As illustrated, the source of heatcomprises electrical heater panels 38, 40 and 42.

The disposition of the heater panels results in a chamber on oppositesides of panel 40. A container 44 is supported between the panels 38 and40. A similar container 46 is supported between the panels 40 and 42.The containers 44 and 46 are open at opposite ends and form a part ofhousing 12. As shown more clearly in FIG. 2, the containers 44 and 46lack a top wall and a bottom wall and having their bottom edge restingon wall 30. The side walls of the containers 44 and 46 which arejuxtaposed to a heater panel are provided with a plurality of spacedapertures 48. The purpose of the apertures 48 will be made clearhereinafter.

The containers 44 and 46 may be supported within the housing 12 in anyone of a wide variety of manners. For purposes of illustration, thecontainers 44 and 46 are provided with a bracket 50 which rests on abracket 52 extending inwardly from the walls of the housing 12 as shownmore clearly in FIG. 4. While only two containers are illustrated inassociation with housing 12, it will be appreciated that one or morecontainers may be utilized. If a large number of containers are utilizedin the housing 12, the efficiency of the apparatus is greatest when aheater panel is juxtaposed to an apertured side wall of each container.

The manner in which electricity is coupled to the heater panels 38-42may assume a wide variety of forms. For purposes of illustration, therear wall 20 is provided with electrical receptacles 54 and 56 intowhich a stud on the panels extend thereby coupling electricity to thepanels. A stud made from an electrically non-conductive material extendsfrom the opposite end of the heater panels for facilitating mounting ofthe panels in spaced parallel planes as shown by comparison of FIGS. 2and 3.

A means is provided to selectively reduce the pressure within thehousing 12. Such means includes a manifold 58 which is in communicationwith the interior of housing 12 my means of pipes 60, 62 and 64. Asillustrated, the pipes 60-64 extend through the front wall 18. It willbe appreciated that the pipes could extend through the rear wall 20 ifdesired. The important relationship of the pipes 60, 62 and 64 residesin the pipes communicating with the interior of the housing 12 in theregion between the perforated side walls of the containers and theheater plates. Hence, pipe 62 communicates with the interior of thehousing 12 in the region between the juxtaposed side walls of thecontainers 44 and 46 and the heater pipe 40. The purpose for thisrelationship will be made clear hereinafter.

When a plurality of housings such as housings 12, 14, and 16 areinterconnected in modular form, it may be desirable to provide aselectively operable valve 66 in the manifold 58. The manifold 58 is incommunication with a condenser 68. A vacuum pump 70 is in communicationwith the manifold 58 through the condenser 68. If desired, twocondensers may be utilized in parallel so that one condenser may beconnected to the system while the other condenser is being frosted.

The material to be dried is preferably in powdered or granular form.Such material may be disposed within the hopper 72 having a dischargecontrol member 74. Member 74 may be a selectively operable valve or thelike. The hopper 72 is preferably supported by a bracket 76 on a mobilevehicle which may be moved to a disposition so that the dischargeopening of the hopper 72 will be over one of the containers 44 and 46.

Guide plates 78 and 80 may be disposed beneath the housing 12. Theplates 78 and 80 may be disposed at an angle so as to cause driedproducts to funnel into one of a plurality of receptacles 82 supportedby an intermittently operated conveyer 81. Any one of a wide variety ofmeans may be provided to receive the dried product or feed the productto be dried into the containers 44 and 46.

In FIG. 5, there is disclosed an alternative embodiment for thecontainers. Hence, the container 84 may be substituted for thecontainers 44 and 46. The container 84 differs from the containers 44and 46 by having elongated vent openings 86 in its major side walls. Thevents 86 are provided by bending a lip portion of the side wall of thecontainer 84 inwardly. In this manner, small shields are provided whichreduce the tendency of the product to be dried to flow out of thecontainer. Such tendency exists when the product is in powdered form.

The apparatus 10 is utilized as follows:

The apparatus 10 may be utilized as a vacuum drying apparatus or afreeze drying apparatus. For purposes of illustration, the descriptionhereinafter will be directed to use of the apparatus 10 for freezedrying products. The products to be freeze dried is preferably inpowdered or granular form and in a frozen state. In this frozen state,the product to be freeze dried is conveyed and discharged into thehopper 72. The bottom wall 30 will be in its closed disposition asillustrated in FIGS. 1 and 2. The top wall 26 will be in the phantomposition illustrated in FIG. 1. Thereafter, the control member 74 willbe manipulated so as to sequentially fill the containers 44 and 46 withthe product to be freeze dried.

Thereafter, the top wall 26 will be closed, a control means will beactivated to cause the panels 38, 40 and 42 to radiate heat, and vacuumpump 70 will be initiated. The product to be freeze dried will besubjected to a reduced pressure and an elevated temperature for acontrolled period of time according to empirical formulas well known tothose skilled in the art depending upon the nature of the product. As aresult of the reduced pressure, and the elevated temperature, the ice inthe frozen product is caused to sublime. The resultant moisture exitsfrom the containers 44 and 46 through the apertures 48 and is removed bythe condenser 68.

The ability of the product to absorb radiant heat from the panels 38-42is increased by making the containers 44 and 46 so that they have a highemissivity. Preferably the containers 44 and 46 are colored black. Heatfrom the panels 38-42 is reflected away from the walls of the housing 12by means of the layer 36. Preferably, the color of the layer 36 iswhite.

After the drying cycle has been completed, the pump 70 may be stoppedand the current for the panels 38-42 may be interrupted. Thereafter, thebottom wall 30 will be manipulated to the phantom position illustratedin FIG. 1. As the bottom wall 30 is pivoted to its open disposition, thedried product falls due to gravity. The guide plates 78 and 80 funnelthe dried product into a suitable receptacle 82. A further decrease inmaterial handling may be accomplished by providing the receptacles 82 onan intermittently operated conveyor 81. However, it will be appreciatedthat any suitable receptacle may be utilized to collect the driedproduct.

Thereafter, the above sequence of events may be repeated. Hence, it willbe seen that the necessity for providing trays or other containers whichare manually placed into and removed from the drying apparatus iseliminated thereby substantially reducing the material handling prior toand after the drying cycle.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification as indicating the scope of theinvention.

I claim:
 1. A product flow through drying apparatus comprising a regular parallelepiped housing, upper and lower ends of said housing having selectively movable portions so that products to be dried may be inserted into the housing from an upper end and removed from a lower end, an open ended container within said housing and supported thereby, said container being adapted to receive a product at its upper end and permit discharge of the product through its lower end, opposite sides of said container having apertures providing open communication between the interior of said container and the interior of said housing, heating panels juxtaposed to the apertured sides of said container for radiantly heating product within said container, said heating panels being disposed in spaced apart relation between the apertured opposite sides and the adjacent side walls of the housing, and means coupled to said housing for reducing the pressure within said housing and said container, said last-mentioned means including conduit means communicating with the interior of said housing through a wall perpendicular to the said adjacent walls, said conduit means being positioned on said perpendicular wall so as to be aligned in communication with the open space between said heater panels and said apertured sides of said container.
 2. A drying apparatus in accordance with claim 1 wherein the movable portions of the ends of said housing constitute the entire top and bottom walls of said housing.
 3. A drying apparatus in accordance with claim 1 wherein the upper end of said container is spaced from the top wall of said housing so that the upper end of said container is in open communication with the interior of said housing.
 4. A drying apparatus in accordance with claim 1 including means pivotably mounting said top and bottom walls on said housing, and latch means for selectively retaining said bottom wall in a closed disposition.
 5. Apparatus in accordance with claim 1 wherein the apertures in the sides of said container are elongated, integral lip portions of said container sides extending inwardly from the upper edge of the elongated apertures, whereby said lip portions assist in preventing a product being dried from flowing freely out of the container by way of the aperture.
 6. A product flow through drying apparatus comprising a regular parallelepiped housing, a selectively operable top wall means on said housing for providing for the selective introduction of a product into said housing, a selectively operable bottom wall means on said housing providing for the selective discharge of a product from said housing, first and second spaced container within said housing, said containers being adapted to receive a product at the upper end and permit discharge of the product through the lower end, said containers being rectangular in transverse section and spaced from the side walls of said housing, each container having apertures in a pair of opposite sides, said containers being disposed side by side within said housing, means on said housing side wall for supporting each container so that the lowermost edge is juxtaposed to the bottom wall means whereby a product in said container will be supported by said bottom wall, the upper edges of said containers being spaced from the top wall means for said housing so that each container is in open communication with the interior of said housing, said bottom wall means having a movable portion at least as large as the combined cross-sectional area of said containers, each container being open at the upper and lower ends thereof, a heating panel juxtaposed adjacent apertured sides of said containers for radiantly heating a product within said containers, and an additional panel being juxtaposed to the opposite apertured side of each of said containers whereby three heater panels are within said housing, and means for selectively reducing the pressure within said housing, said means for selectively reducing the pressure within said housing including at least three conduits communicating with said housing through walls perpendicular to the apertured sides of said containers at points generally aligned with the open space between said heater panels and said apertured sides.
 7. Apparatus is accordance with claim 6 wherein said apertures in the sides of each container are elongated, integral lip portions of the container sides extending inwardly from the upper edge of the elongated apertures, whereby said lip portions assist in preventing a product being dried from flowing freely out of the containers by way of the apertures. .Iadd.
 8. Apparatus for bulk freeze-drying of heat-sensitive material which has been frozen into a granular particle form comprising a series of aligned and substantially vertical product cells separated by open spaces having substantially the same height and length as said cells, said cells having opposed walls of relatively large surface area in relation to the thickness of said cells, said walls being permeable to free passage of water vapor into said open spaces; means for sealing said product walls from atmosphere; vacuum means for lowering the pressure in the open spaces adjacent to each product retaining wall to assure sublimation into said spaces; means for applying heat to provide heat of sublimation; means for removal of water vapor; and means for discharging said product from the vertical product beds by the force of gravity. .Iaddend..Iadd.
 9. The apparatus of claim 8 wherein the vertical cells are in the form of elongated, substantially rectangular product retaining cells; the walls of said cells having a sufficient number of openings therein for free passage of water vapor to the open spaces. .Iaddend. 